Delayed cytogenetic and major molecular responses associated to increased BMI at baseline in chronic myeloid leukemia patients treated with imatinib.

Obesity, measured as body mass index (BMI), has been identified as a possible risk factor for several solid tumors as well as for chronic myeloid leukemia (CML). To date, no correlations have been reported in this latter disease between BMI at baseline and response to targeted therapies. We refer here on the impact of BMI on clinical response in 339 chronic phase (CP) CML patients treated with imatinib and 35 CP-CML patients treated frontline with nilotinib. If compared to patients with low BMI (<18.5-25), patients with increased BMI (>25-40) at diagnosis who received imatinib showed a significantly longer median time to achieve complete cytogenetic response (6.8 months vs 3.3 months, p=0.001), a reduced rate of major molecular response (77% vs 58%, p=0.01) which was also achieved in a longer median time (29 months compared to 14 months, p=0.01). Conversely, no differences were revealed with respect to BMI in patients treated frontline with nilotinib and also patients with increased BMI obtained rapidly CCyR and MMR with an incidence similar to that of underweight/normal weight patients. These results suggest that CML patients with increased weight at baseline should be followed and carefully monitored if treated with standard dose imatinib frontline for a possible early switch.